1. Field
The present invention relates to a display device.
2. Description of the Prior Art
A display device is a device that visually displays data. The display device may be a liquid crystal display, an electrophoretic display, an organic light emitting display, an inorganic EL (Electro Luminescent) display, a field emission display, a surface-conduction electron-emitter display, a plasma display, or a cathode ray display.
Among them, the organic light emitting display is a display device that displays information, such as an image or text, using light that is generated through combination of holes and electrons, which are respectively provided from an anode electrode and a cathode electrode, in an organic layer that is positioned or located between the anode electrode and the cathode electrode.
Recently, a digital driving method, e.g., a constant voltage driving method, has been adopted for use with organic light emitting displays. The digital driving method enables the organic light emitting display to smoothly implement a high-resolution image using a simple Integrated Circuit (IC) structure. Further, because the digital driving method is a driving method that uses an on/off state of a driving thing film transistor (TFT), it is scarcely affected by the picture quality deterioration phenomenon due to the deviation (or variations) of TFT characteristics in a panel, and thus it is suitable for implementing a large-size panel.
However, the organic light emitting display adopting or utilizing a digital driving method may exhibit an IR-drop phenomenon, and if a voltage that is applied to a pixel is decreased, current that flows thereto may abruptly decrease. For example, if a voltage that is applied to a green pixel is decreased from 6V to 5V, the current that flows through the green pixel is decreased by about 60%.
The current decrease due to the IR-drop phenomenon may cause a difference in luminance between positions of a display region on which an image is displayed. Recently, with large-sized organic light emitting displays, the luminance difference between the positions of the display region has been further increased.